In semiconductor vacuum processing, evacuated process chambers generally include mechanical devices for accurately handling and moving semiconductor slices therein. In such chambers, it is desirable to minimize the material handling mechanisms that must be located inside the chambers To accomplish this, it is preferable to locate the necessary power elements such as motors outside the chamber. Power must then be transmitted from the power elements to the mechanism by couplings such as vacuum feed-through devices. In order to enable cleaning or repair of the internal driven mechanism, it is desirable to have a separable coupling which will allow removal of the driven mechanism from the power elements.
Separable couplings are currently available, but due to their design characteristics, they require clearance between their mating parts to allow them to be separated. This clearance may be unimportant when the coupling is used only as a power transmitting device. However, when shaft positioning is critical, as it is in mechanical handling devices for semiconductor vacuum processing, this clearance results in backlash between the driving and driven shafts that decreases the accuracy of the driven shaft's rotary position.
Thus, a need has arisen for a separable shaft coupling with zero backlash that can be coupled and uncoupled in an area such as semiconductor vacuum processing where visual and physical access to the coupling is impractical or undesirable.